RESPONSIBLE RETROFIT PRINCIPALS FOR ADDRESSING THE CLIMATE EMERGENCY IN EXISTING BUILDINGS A ‘whole building’ approach A responsible approach to retrofit should be founded on the principle that the greenest (and cheapest) energy, is the energy you don’t use. A ‘whole building’ approach considers the building as a system of interconnected materials, functions and users. Starting from a position of knowledge, understand how the building is working and what needs to be done. Reducing carbon emissions is more than simply insulating and adding solar panels. Much can be achieved by changing behaviour, avoiding waste, using efficient controls and equipment, and managing the building to its optimum performance. Traditional buildings were constructed to be ‘breathable’ using vapour-permeable materials. Incorporating materials that enable this permeability is crucial to avoiding unintended consequences like moisture buildup and damp. A risk-based approach will help effectively manage this.
Beyond net zero Reducing carbon emissions relating to a building’s operation is vital to addressing the climate emergency, but this should not be considered in isolation. Embodied carbon emissions associated with new materials and wasteful construction practices are also significant. In addition, projects should consider how a building can contribute positively to factors such as comfort and health, biodiversity and water efficiency.
KNOWLEDGE
defects, damp, draughts, cold bridges, occupant behaviour, space use
Mitigate the impact of unavoidable energy and resource use
MITIGATE
ACTIVE
context, history, significance, construction, condition, lifespan, occupation, energy use, budget
Eliminate unnecessary energy and resource wastage
ELIMINATE
IMPROVE
Understand the building, its context and impact
Passive measures, insulation, solar shading, window and door upgrades, air tightness
photovoltaics, solar hot water panels, heat pump, district heating/cooling network, biomass Roof: ~25% heat loss
Responsible Retrofit Hierarchy - a planning tool for the early stages of a project
Solar panels can be integrated on or off the building depending on space.
Damp fabric is 30% less efficient at retaining heat than dry fabric.
High performing replacement or secondary glazing can reduce heat loss without impacting heritage. Windows: ~10% heat loss
A ‘Whole Building’ Approach considers the building as a system of interconnected materials, functions and users
Applications to the local planning authority for planning permissions and/or listed building consent may be required for certain energy efficiency measures. Detailed site specific advice will be available from the local planning authority.
Air source heat pumps run at low temperatures and are most effective when combined with fabric upgrades.
The roof is one of the most important and effective areas to provide better thermal efficiency.
Financing and funding
Useful links
Rainwater and grey water harvesting can reduce potable water use and carbon emissions.
Surrounding trees and buildings can have an impact on energy use e.g. providing solar shading.
Responsible Retrofit Guidance Wheel, STBA Planning permission guidance, GOV.UK Public Sector Decarbonisation Scheme, GOV.UK Energy-saving materials and heating equipment VAT notice, GOV.UK Energy efficiency and historic buildings, Historic England
Using spaces efficiently will help mitigate the impact of unavoidable energy use.
Walls: ~35% heat loss
Shutters can reduce risk of overheating in summer, whilst wall hangings & curtains can help keep heat in.
Proposed energy efficiency measures may also require approval under the Building Regulations. Early consultation can help ensure that works are appropriate and compliant.
Funding may be available depending on location and building type. For example: Public Sector Decarbonisation Scheme (PSDS), Social Housing Decarbonisation Fund (SHDF), or Heritage Lottery Funding (HLF). Residential projects may also be eligible for VAT deductions.
Fabric upgrades must consider moisture movement to avoid risk of condensation.
Introduce appropriate zero carbon energy technologies
Legal and regulatory requirements
Whole Life Costing considers a building’s cost over its full life span and is important in achieving best value from both the capital costs of construction and the related ongoing costs of operating it.
Traditional buildings were constructed to be ‘breathable’ - using vapour permeable materials.
Improve performance of existing building fabric and services
Allow time early on in the process to properly understand the building, how energy is being wasted and what factors are impacting this. Follow this with a thorough analysis of the available options, and their respective impact on the building, heritage, carbon and costs.This will ensure the right solutions are implemented.
For a scheme to be successful, adequate funding and access to appropriate professional expertise and practical skills will be needed.When considering how to plan and budget for any retrofit works the following should be considered:
Chimney stacks are important for natural ventilation.They can be used to discretely locate new services.
LED lighting, energy efficiency appliances and controls, low flow fittings, efficient use of space
Timescales and programme
Some retrofit work can be intrusive.When planning what work is needed, it is important to consider the inevitable disruption this may cause. In some instances it may be better to do all the work at once, in others, it will be necessary to phase the work over a number of years.
The greenest and cheapest energy is the energy we don’t use
Simple repairs to mend cracks and gaps can significantly reduce heat loss through infiltration or draughts.
Draughts: ~15% heat loss
Implementing ‘low hanging fruit’ measures like LED lighting can be relatively low cost.
Floors: ~15% heat loss
Not all parts of a building will have the same age, construction and performance.
Ground source heat pumps are more discrete than air source, but are more intrusive.
© Purcell 2022